MB39A113 Datasheet, PDF (30/51 Pages) Fujitsu Component Limited. – ASSP for Power Supply Applications (Secondary Battery)

MB39A113
VD × ID × tr × fosc
PS (ON) =
6
25 × 3 × 15 × 10^−9 × 300 × 10³
=
6
=: 0.056 W
PS (OFF) =
=
=:
VD × ID (Max) × tf × fosc
6
25 × 3.6 × 42 × 10^−9 × 300 × 10³
6
0.189 W
PT = PC + PS (ON) + PS (OFF)
=: 0.109 + 0.056 + 0.189
=: 0.354 W
The above power dissipation figures for the µPA2714GR are satisfied with ample margin at 2.0 W.
Setting 12.6 V
Input voltage VIN = 22 V, output voltage VO = 12.6 V, drain current ID = 3 A, oscillation frequency fosc = 300 kHz,
L = 15 µH, drain-source ON resistance RDS (ON) =: 18 mΩ, tr =: 15 ns, tf =: 42 ns
Drain current (Max) : ID (Max)
VIN−Vo
ID (Max) = Io +
tON
2L
= 3+
22−12.6
2 × 15 × 10^−6
1
×
× 0.572
300 × 10³
=: 3.6 A
Drain current (Min) : ID (Min)
VIN−Vo
ID (Min) = Io −
tON
2L
22−12.6
= 3−
2 × 15 × 10^−6
1
×
× 0.572
300 × 10³
=: 2.4 A
PC = ID2 × RDS (ON) × Duty
= 3² × 0.018 × 0.572
=: 0.093 W
30